Improving Your Automobile

Car Trouble? 4 Prospective Causes Resulting In A Non-Functional Speedometer

4 August 2016

Addison Morris

A malfunctioning speedometer can lead to several car problems or accidents because of your inability to calculate your car's speed accurately. The Australian Design Rule (ADR) 18 requires the speedometer of all cars manufactured after July 2006 to have a speed greater than or less than the true speed with an accuracy of 10 percent plus 4 km/h. If you find the speedometer inaccurate, then it's probably because of these causes. A mechanic will need to rectify the problem to ensure it complies with regulations.

Faulty Engine Control Unit (ECU)

If your engine control unit is damaged or faulty, then you may have trouble with your speedometer. The ECU monitors every facet of your car and maintains a link between the speed sensor and the speedometer. A damaged ECU will result in your check engine lights turning on. ECUs typically get damaged because the battery has been overcharged or because of internal overheating.

Damaged Speed Sensor

If you have a problem with your speedometer, it could be because the speed sensor has stopped functioning. This sensor is located near the front axle and works to send information to the car's computer system regarding the speed of the engine. Sensor faults could occur because of a defective coil pack or a bad throttle position sensor. The speed sensor can also get damaged when your car has been in an accident and has been dented externally. Speed sensor problems may also arise because of faulty wiring. A qualified mechanic will have to open up the system to identity and repair the issue.

Broken Gear Head In The Speedometer System

The gear head within your speedometer system could potentially break because of a damaged cable, which is either trodden or tattered. If you notice the speedometer needle swinging wildly or moving sluggishly, then it's probably because of a broken gear head that may need replacement.

Broken Fuse Or Poor Wiring

Wiring can be damaged over time because of poor vehicle maintenance. If the wire connecting your speedometer to the engine is frayed or broken, then you will not get a reading of your speed. If a fuse blows or is faulty inside the vehicle, then the speedo will likely stop working. The fuse box is typically found under the glove compartment. Your mechanic will need to explore all the components within the electrical system to identify the cause of speedometer failure.

Make sure you get a qualified mechanic to tackle these problems because a faulty speedometer is a violation of the regulations set by the ADR. Make sure your car is regularly maintained to prevent these problems from happening frequently.  

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